Treatment of spinnerettes to prevent accumulations thereon



STATE-S PATENT OFFIC TREATMENT OF SPINNERETTES TO PRE- VENT ACCUMULATIONS THEREON Henri L. Barthelemy and Glover Hood Robinson, Rome, Ga...assignors, by mesne assignments, to American Enka Corporation, Enka, N.C., a corporation of Delaware Application April 25, 1941, Serial No.390,334

' 11 Claims. (01. 18-8) This invention relates to the spinning ofvisthat, as a result thereof, the solid materials which cose rayon andhas for its object the provision accumulate in the spin-bath, such asprecipiof certain improvements in spinning apparatus tated sulphur,salts, complex compounds, etc., do and methods for suppressing theformation of not accumulate in and on the spinnerettes and incrustationsand craters which form on metallic form the incrustations and craters asthey do in spinnerettes. It is an object of the invention to th saidpractices. provide a methodof treating metallic spin- As a result of ourinvestigations and discover- 4 nerettes to produce an improvedspinnerette as ies, we have found that a sort of micro-film or a well asan improved arrangement of spinning cation-active compound can be causedto form apparatus for employing the improved spinon, or attach itselfto, the metallic surface of a nerette. spinnerette and that it adheresthereto with a The invention contemplates the treatment of good degreeof stability. Moreover, we have dismetallic spinnerettes with acation-active comcovered that when, for instance, a gold-platinum poundto form a thin coating of the compound spinnerette is immersed in anyMuller type of on the surface of the.spinnerette, and particuspin-bath,the splnnerette acquires a negative larly that portion thereofimmediately surroundcharge which varies from about 50 to 300 milliingthe orifices. The coating of cation-active volts. This potential isapparently of sufllcient compound is a very thin film, what may beremagnitude to prevent too quick a difiusion into garded as a sort ofmicro-film, and will hereint e bath f e C c ve C mpo forming after, forconvenience, be called simply a film. the film. The time of protectionafforded is The invention aims to provide an improved spinabout to days.We have found that a film ning method employing spinnerettes coated'withof the cation-active compound may be formed a cation-active compound andthe maintenance on the metallic surface of spinnerettes by'treatof aspinning environment which preserves the ing the spinnerettes with anaqueous solution of film in stable attachment on the spinnerette. 20 acation-active compound under conditions which We have found that a filmof a cation-active eliminate the air layer on the metallic surfacecompound when applied toa metallic spinnerette and permit the film toform thereon. A very will enable the spinnerette to be used in a viscoseeffective method of accomplishing the removal spin-bath for relativelylong periods without the 4 of the gas film and forming the film ofcationaccumulation of incrusting substances near the active compound isto treat the spinnerettes in a outer surface of the orifices and whichhave hereboiling aqueous solution of the cation-active comtofore formed,especially in spin-baths free of pound for about fifteen minutes.However, fair cation-active compounds or rich in zinc sulphate. resultscan also be obtained by performing the Spinning operations carried outby using the same treatment in hotor lukewarm solutions, film coatedspinnerettes of the invention will 3. preferably with the-help of asmall difierence of produce, over relatively long periods of time,electrical potential to promote the migration of filaments of uniformnormal denier and with the cation to the spinnerette, I practically nominute filaments such as cus- The optimum concentration of cation-activetomarily result from the accumulations of solid material in water isdetermined by systematic matter in the form of craters around, and in--0 tests, as cation-active compounds found on the crustations in, theorifices. market exhibit different activities, and as ex- In practicesheretofore proposed and also comperience taught us there exists for eachone an mercially used, cation-active compounds are optimum concentrationabove which spinning either mixed with the spinning solution, ordisstability is impaired again. solved in the spin-bath for the purposeof pre- The invention in its more or less complete venting orsuppressing the formation of the craaspects contemplates the provisionof an imters and incrustations. In the said practicesit proved spinningmethod which comprises emis necessary to use a relatively large quantityof ploying a metallic spinnerette coated with a film the cation-activecompound in the spinning soluof a cation-active compound underconditions tion, or in the spin-bath, as the case may be, in 5 causingthe spinncrette to be under a negative order to effect a suppression ofthe accumulations electrical potential. In. spinning viscos rayon in andon the spinnerettes. It has been the prein accordance with theinvention, th liquid envailing belief that the cation-active compoundsvironment in contact with the spinnerette .is have a pronounced effectupon the surface tenkept substantially free of anion-active compoundssion of the medium in which it is dissolved and or other like materialsor conditions tending to (30%) of platinum, is

displace or inhibit the cation-active compound from its stableattachment to the spinnerette.

In the accompanying drawing: Fig. l is a side view of a metallicspinnerette having a film or a cation-active compound on its surface,and Fig. 2 is a diagrammatic illustration of apparatus which may be usedin a method of the invention.

In practicing the invention for producing a spinnerette coated with afilm of cation-active compound, a metallic spinnerette, especially oneformed of noble metal, for example a spinnerette formed of an alloycontaining approximately seventy percent (70%) of gold and thirtypercent thoroughly cleaned to remove adhering solid and liquid matter.The

cleaned spinnerette is submerged in a solution comprising, for example,approximately two grams of lauryl pyridinium chloride in one liter ofdistilled water. The solution is boiled for a sufiicient length of timeto eliminate surface gases, about fifteen minutes being ordinarilysuitable to accomplish this purpose. As the film of gas is removed fromthe surfac of the spinnerette, the cation-active compound attachesitself to the surface of the spinnerette in the form of a film whichseems to have the characteristics of a micro-film. In applying the filmof cationactive compound to a metallic spinnerette in the apparatusillustrated in Fig, 2, an aqueous solution of a cation-active compound,like lauryl pyridinium chloride, is heated in the basin until it becomeswarm or hot and a small difference of electrical potential is applied tothe spinnerette by means of the battery, to promote the migration of thecations to the spinnerette.

The spinnerette coated with the cation-active compound is removed fromthe solution and is thereafter dried in any suitable manner to removethe water, due precautions being taken not to disturb or injure thefilm. A satisfactory manner of removing the water is accomplished byheating the spinnerette in a ventilated drier at a temperature notexceeding 65 C.

The coated spinnerette is attached to the spinning apparatus in theusual' way, care being taken not to touch or otherwise disturb the filmon the surface of the spinnerette in the immediate vicinity of theorifices. covers the large surfaces of the spinnerette, but seems tocover and coat the walls of the orifices themselves. The film appears toprevent wetting of the spinnerette by the spin-bath and also wetting ofthe insides of the orifices by the viscose solution. So long as thespinnerette is under a negative potential and the spin-bathsubstantially free of anion-active compounds, the film on the surface ofthe spinnerette remains in stable or firm adherence notwithstanding thesolubility in the aqueous spin-bath of the cation-active compoundforrning the film.

While many cation-active compounds are suitable for the purposes of thisinvention, we have found that lauryl pyridinium chloride, cetylpyridinium bromide (sold by du Pont under the trade name Fixanol), and aproduct sold by Carbide and Carbon Chemicals Corporation under its tradenam Amine 22L are desirable because of their effectiveness andavailability.

Spinnerettes formed of the noble metals, for example gold, platinum andpalladium and alloys thereof, have negative potentials when in thepresence of acid spinning baths and may be used The film not only in theapparatus and method of the invention. 7

Spinnerettes formed of tantalum may likewise beused.

In the usual viscose spinning operation, and particularly in thoseoperations which employ relatively large quantities of zinc sulphate inthe spin-bath, the orifices of the metallic spinnerettes becomeincrusted with solid matter of indefinite composition, which alsofrequently forms craters around the orifices. These incrustations and/orcraters obstruct the free passage of spinning solution through theorifices, causing what is known as slow holes. These slow holes causethe filaments to be much smaller in diameter than they would normallybe. These incrustations and craters form at such a rapid rate that thespinnerettes must be subjected to frequent inspection, for example onceevery forty-eight hours, to keep them in operating condition. Inspectionincludes removing the spinnerettes from the spin-bath, rubbing thesurface with the thumb to remove the craters and seeing whether the flowfrom any of the holes appears sluggish. If the flow is sluggish, thespinnerette must be dismounted and replaced. When, however, thespinnerettes are coated with a film of a cation-active compoundaccording to the invention, they may be operated continuously for a weekor more without inspection and without producing any appreciablequantity of minute filaments.

The invention not only eliminates the necessity of contaminating theviscose and the spinbath with a cation-active compound in order toeliminate incrustations and craters, but it also reduces the quantity ofthe compound necessary for the purpose to almost an immeasurably smallquantity.

We claim: I

l. A metallic spinnerette comprising a film of a cation-active compoundin stable attachment on the surface of the metal.

2. Apparatus for the spinning of viscose which comprises a metallicspinnerette having a film of a cation-active compound, and means formaintaining said spinnerette under a negative electrical potentialduring spinning.

3. The method of treating a metallic spinnerette which comprisescleaning the spinnerette to remove solid or liquid matter, submergingthe cleaned spinnerette in a hot solution of a cationactive compound fora sufiicient time to permit the cation-active compound to displace gasfrom the surface of the spinnerette and to form thereon a film of thecation-active compound.

4. The method of treating a metallic spinnerette which comprises heatingthe spinnerette in an aqueous solution of a cation-active compound for asufficient time to form a film of the cationactive compound on thesurface of the spinnerette.

' 5. The method of treating a metallic spinnerette which comprisessubmerging the spinnerette in a .boiling aqueous solution of acationactive compound for a sufficient time to form a film of thecation-active compound on the surface of the spinnerette, removing thespinnerette from the solution, and evaporating water from the surface ofthe spinnerette. I

6. In a method of spinning viscose, the improvement which comprisesemploying a metallic spinnerette having in stable attachment on itssurface a film of a cation-active compound, maintaining the spinneretteunder a negative electrical potential, and maintaining the liquidenvironment in contact with the spinnerette sufficiently free'ofanion-active compounds to maintain the film of cation-active compoundfor a relatively long period.

7. In a method of spinning viscose, the improvement which comprisesapplying a film of a cation-active compound on the spinnerette, placingthe spinnerette in the spin-bath, and maintaining the spinnerette undera negative electrical potential and the spin-bath free of anionactivecompounds that will displace the said film.

8. A spinnerette formed of a. noble metal comprising a film of a.cation-active compound in stable attachment on the surface of the metal.

9. Apparatus for the spinning of viscose which comprises a spinneretteformed of a noble metal having a film of a cation-active compound, and

, 3211sv f9. ,maintaining said spinnerette under a v negative electricalpotential during spinning.

10. In a method of spinning viscose, the improvement which comprisesemploying a spinnoble metal having in stable HENRI L. BARTHELEMY. GLOVERHOOD ROBINSON.

